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Detecting small quantities of residual vinyl chloride monomer URL 17419 S. C. Gilbert, J. R. Giacin, J Department of-Food Science Rutgers University New Brunswick, New Jersey R. Morano, & J. D. Rosen - -rLu, i-v'-''-. JLih-rn^Ci /ml L <i1' " Introduction. Attention has recently been focused on the health hazard to the general public from residual vinyl chloride monomer (VCM) in polyvinyl chloride (PVC) based polymers. The need for this scrutiny has arisen from the findings of an unusually high inci dence of angiosarcoma in humans exposed to high concentrations of VCM (ca. 1000 ppm) through occu pational exposure over long periods of time (1). This relationship has been strengthened greatly with direct experimental evidence of angiosarcoma in mice exposed to VCM dosages at levels as low as 50 ppm (inhalation) over an eight month period (2). The concern for the general public arises from the mag nitude of the annual PVC production (about 5 billion pounds in 1973, (3)) and its use in packaging consumer products. There are two distinguishable areas for concern. The first is that of exposure through inhalation of the highly volatile gas, either by occupational exposure through release to the atmosphere or by its use as a propellant. Present regulations by EPA ban the latter (4), while recent OSHA rulings specify a reduction to 1 ppm in the atmosphere of factories involved in PVC production and use (5). Five ppm is allowable fpr periods shorter than 15 minutes. The second area of concern involves the possibility of exposure by ingestion of VCM as a result of its mi gration to food contacted with PVC in packaging ma terials. We estimate approximately 250 million pounds of PVC may be involved annually in food packaging at present levels (6). The regulatory aspects of this type of contact are within the jurisdiction of FDA under the category of "incidental food additives." These regulations specify that: "A material used in the production of containers and packages is subject to the definition (of food additive) if it may reasonably be expected to become a component.... of food packaged in the container." The regulation further states that: "If there is no migration of packaging component from the package to the food, it does not become a component of the food and thus is not a food ad ditive" (7). The FDA Guidelines tentatively define Summary: This article summarizes procedures for de tecting small quantities of vinyl chloride monomer in packaging materials. The lower limit of detection by gas chromatography (flame ionization detector) was 2.2 x 10~* gm, which is equivalent to a concentration limit of 5 ppb (w/w) in a polymer sample. Gas chromatography supplemented by a form of mass spectrometry known as mass-fragmentography was also employed, allowing detection of 8.7 x 10~>2 gm VCM. The authors point out that eliminating materials to the limits of detectability may have more serious ill effects than allowing reasonable levels of suspect ma terial to be present. "no" as if computations show that no more than 0.01 ppm of a substance would be added to food assuming it all migrated. The extracts usually need not be tested for such a substance" (8). In the absence of carcinogenesis, the 1 x 10~*g/g level of additive (migrant) in food has been accepted as the equivalent of "no." Where carcinogens are concerned, the equivalent "no" has not been defined, except in the vague terms of the most sensitive analytical techniques available for quanti fication of the substance in question. The Delaney Clause states that, "no additive shall be deemed to be safe if it is found to induce cancer when ingested by man or animal, or if it is found, after tests which are appropriate for the evaluation of the safety of food additives, to induce cancer in man or animal, ..." (9). Therefore, the concern with re sidual VCM in PVC packaging material is whether or not VCM migrates from PVC to the food contained in the package. In this paper we deal with the question of VCM mi gration from PVC to foods. As a first step, an analytical procedure for the quantitation of vinyl chloride was developed. For the past ten years, our laboratory has been in volved with migration and desorption studies as a means of evaluating the interaction between low This article was adapted from a paper presented at a meeting of the section of Pnlymer Science. The manuscript is in press by the New York Academy of }mi k jk'- iU'vr-di|>i|uly/4iinnl l'l/S n n u fi molecular weight compounds and polymers. These studies have dealt with various aspects of migration ranging from the practical problem of migrants affecting sensory properties of packaged food (10) vO theoretical studies where sorption-desorption thermodynamic parameters were evaluated (11, 12). Gaseous migrants have also been used as probes for the study of macromolecular structure (13). Studies on sensoriaily important residues have shown that contact of the polymer with such substances in the normal manufacturing process resuited in measurable sorption or retention, even under the extremes of commercial conditions used for their removal (14). The method developed for the determination of such residues is now an accepted American Society for Testing and Materials (ASTM) procedure (15). The apparatus is shown schematically in Figure 1. This method involves distillation of vo latile residues from the polymers into a hermetic limited volume at sufficiently elevated time/ temperature conditions so as to provide essentially complete transfer from solid to gaseous phase. Gas chromatographic analysis (GLC) of the gas phase then gives tentatively, both a qualitative identification and quantitative upper limit for the presence of the residue in question. This gas phase partition has been related to liquid phase transfer in certain cases with good agreement between methods (16). The extension of this method to the measurement of residual VCM in PVC film and resin has been es tablished in our laboratory. In addition, the feasibility of using mass fragmentography for the analysis of VCM in headspace gas has been determined. This method of detection was found to be immediately applicable to air sampling (17). Materiab and methods. The appratus used con sisted of: (a) Gas chromatograph. Hewlett-Packard Model 1520 gas chromatography, equipped with back flush valve. GLC conditions: 10* x W' i.d. stainless steel column packed with 10V* SE30 on 90-100 mesh Anakrom ABS. Nitrogen flow rate 60 ml/min.; temperatures (*Q-- injection port 170*, detector 220*, column main tained at ambient temperature. Vinyl chloride reten tion time, 2j0 min. Inject 10 ml sample with gas tight syringe, equipped with one-way metal stopcock valve. <b) Hot jar. A 250 mi (% pint) Mason jar fitted with stainless steel lid specially fabricated with Swagelock fittings and septum as described by Wilks and Gilbert 04). Weigh accurately sample of PVC film or resin and transfer to Mason jar. The area and volume of PVC film, are recorded prior to analysis. The apparatus utilizing the hot jar and syringe are placed In a 90" C oven and maintained for 30 min. The GLC response obtained from three separate 10 ml on-column injec tions of the headspace is measured. No decom- Figure 1 Apparaius uied to sample gas. Method involves the distillation of volatile residues from the polymers into a hermetic limited volume under elevated lime/temperature conditions. position of the polymer to liberate VCM was detected after prolonged heating (24 hr.) at 90* C. A standard curve of response vs. VCM concen tration was constructed from vinyl chloride mixtures of known concentration. A standard mixture of vinyl chloride diluted with nitrogen was prepared containing 7 ppt (v/v) vinyl chloride and was then used to prepare vinyl chloride mixtures of varying concentrations. (c) Gas chromatography--mass spectrometer. A Du Pont Model 21-490 mass spectrometer, equipped with digital mass marker and dynamic dual ion de tector of the design of Pareies and Rosen (18) was in terfaced to a Varian Model 2740 gas chromatograph via a single-stage jet separator. GLC conditions^ Were similar to those used for GLC detection of vinyl chloride. Vinyl chloride retention time was 1.52 min. Detect vinyl chloride by repeatedly scanning both the m/e 62 and 64 ions. Simultaneously record on 2-pen recorder (17). Inject 10 ml sample with gas tight syringe. Results and discussion. Table 1 represents the lev els of VCM detected in freshly prepared PVC homopolymer and plasticized resin. Also listed is the retained VCM after the two resins were equilibrated in air. As shown in Table I, a marked decrease in residual VCM was found in the resin following plasticizer ad dition. The levels being 254 and 0.59 ppm, respec tively. This decrease in residual VCM may be at tributed to air equilibration as well as losses during processing. In addition, the plasticizer will modify the physical properties of the polymer (e.g., Tg) and, therefore, affect the solubility of VCM in the resin. Table I also shows that the concentration of re sidual VCM in the resins was markedly decreased by equilibration of the polymer samples in air. The level of VCM in the plasticized and unplasticized resins, following equilibration, was 0.02 and 2.0 ppm, respec tively, which represented approximately 7.0 and 1.0% of the initial VCM concentrations. For these studies, polymer samples were transferred from a closed container to an open crystallizing dish and placed in a fume hood for 48 hrs. This favorable partitioning of VCM between PVC and its environment may provide a method of re moving residual VCM from the resin. Analysis for residual VCM in several representative industrial grade PVC products was carried out and the Title i Residual VCM in PVC resin by hot jar technique Sample0 number Resin lype Equilibration00 time (hours) Average000 response Total VCM (gm) 1 Unpiasticiced 0 2 Unplasticized 48 3 Plasticized 0 4 Plasticized 48 1.85 x It)5 1.78 x 103 4.39 x I02 183 x 10 6.35 x 10`4 5.18 x I0"7 1.49 x 10"7 5.33 x IQ'* *2.5 gm. sample of powder used **Samp!e placed in hood ' ***Response for 10 ml injection - range x attenuation x peak height (cm) Average for two runs VCM concentration in resin (ppm) 254.0 2.07 0.597 0.0213 results are tabulated in Table II. As shown in Table II, the detected level of VCM was between 5 ppb for PVC film to 71 ppb for PVC coated fabric. The lower limit of detection of VCM was 2.2 x 10-* gm by flame ionization (FID). Therefore, if a 10 gm sample of PVC film or resin is assayed by the hot jar procedure and we assume ail the vinyl chloride present is released on heating, a detectable limit of 5.6 ppb (w/w) is possible. Conventional GLC procedures for analysis of re sidual VCM in PVC resin require dissolution of the polymer sample in a suitable solvent (e.g., THF) and direct on-column injection of the resultant solution. While this procedure is very useful, the sensitivity of the method is limited by: a. solubility of the polymer sample in the solvent, b. the maximum sample size which can be injected into the gas chromatograph and c. solvent impurities. The sensitivity of the procedure utilizing the hot jar is limited by sample size and reactor (jar) volume and can be easily increased by varying these parameters. This technique, therefore, appears to offer some ad vantages over conventional methodology. That the procedure utilizing the hot jar must be essentially quantitative is supported by the results of Berens (19), who found that above the glass transition temperature (Tg) the solubility of VCM.in PVC resins was negligible. It should be reemphasized, however, that this procedure is valid only in a negative sense in that a GLC method can only establish the maximum amount of a suspected material producing a response in the detector under specified operating conditions but cannot provide positive identification. The need for structural conformation of unknown contaminants (e.g., vinyl chloride) is difficult below the ppm level. We, therefore, employed mass fragmentography, a technique where the mass spec trometer is used as a sensitive and selective detector for GLC effluents (17). For VCM analysis, the parent (m/e 62) and the P+2 (m/e 64) fragments were recorded simultaneously. A ratio of 3 to 1 for these peaks is obtained for vinyl chloride as a result of the natural isotopic distribution of chlorine - 37. Peak heights at these ion mass nqjnbers and a comparison of their ratios combined with the GLC retention time afforded a specific and sensitive method for VCM determination at thed.7 x 10~`* g level, in headspace analysis. The lower FID limit determined on our detector was 2.2 x 10"* g. The mass fragmentography method is, therefore, al most 250 times more sensitive than flame ionization detection with the added advantage of structure confirmation. To date, headspace analysis by this technique has been carried out on standard vinyl chloride mixtures, and the procedure is immediately applicable to air sampling. The application of the procedure using the hot jar with mass fragmentography detection for analysis of residual VCM in polymer samples is presently being investigated. This method when applied to food simulants or to foods themselves is expected to be much more sensitive than the 10~* g/g level presently considered Tabic I! Residual VCM in PVC Blip, coated Toil and coaled fabric by hot jar technique Sample number Film type Sample wt. (gm) Thickness (mil) 1 Plasticized 4.5 0.75 PVC 2 PVC coated 8.0 1.70 foil 3 PVC coated 6.0 -- fabric Average* response00 2.15 x 10* 1.27 x 10 1.35 x IQ2 Total VCM(gm) 6.7 x 10'* 4.0 x 10~* 4.25 x I0*7 VCM eon. in PVC(ppb)000 15 5 71 'Average of two injections ''Response for 10 ml injection - range x attenuation x peak height (cm) These analyses were preformed following major servicing of the instrument which increased the detector sensitivity tenfold to a detection levelof2.2x l0"`gVCM URL 17421 22 iwi k.w tlrvHupmrni |uly/jut<ust V>75 URL 17422 as the "no migration" level. We consider it quite probable that this or equally advanced techniques in analytical chemistry could be developed to dem onstrate the presence of VCM in any sample of PVC and by calculation infer its transfer to PVC packaged food. Studies on desorption of low molecular weight molecules from polymers showed that two factors must be considered in relating VCM partition from polymer to food. The first concerns the equilibrium concentration of migrant in the food and the second is the time required to attain equilibrium. In can be assumed that at any concentration of VCM in the polymer, there will be a correspondingly lower concentration in the contacting food with a maximum at equilibrium. It is quite likely that over three orders of magnitude will be found between the concentration of VCM in the polymer to that in the contacting phase. These assumptions are based on considerations of the partition coefficient and the weight ratio of packaging material to contacting phase. The equilibrium concentration of VCM in a food resulting from contact with a PVC package may be estimated by solution of equation (1). (M], - lMJ^[W/(KWp + W,)l 0) When (MJ, is the concentration of VCM in the food at equilibrium, [M]Po is the concentration of VCM in PVC package at zero time, K is the partition coefficient, and W, and W, are the weights of the PVC package and food phase, respectively. If the following estimates for these factors are made, [M]p<> -lx 10"* g/g, K - 100, Wp - 1 gm and W, - 100 gm; then (M). is equal to [1 x 10-*] <1)/[(1) (100) + (100)1 - 0.5 x 10-* g/g If we assume complete transfer of VCM from the package to food, (M]f- 1 x 10-* g/g. In all probability, at sufficiently low levels of VCM in the polymer, the equilibrium concentration of mi grant in the food will be below that estimated for [MJ, by equation (1) because of nonlinear disorption of the VCM from the polymer. Berens (19) reported such a non-ideal behavior for the VCM/PVC system against VCM vapor. While there Is still considerable question as to the presence of a defined "no effect" threshold, the proposed OSHA standard of 1 ppm (v/v) will be considered as having a sufficient safety factor. The per day level of VCM inhaled by exposure to 1 ppm vinyl chloride (v/v) for 8 hrs. per day with a relative air in take of 1<P liters/day may be estimated by solution of equation (2), after first calculating the density of VCM at STP. g VCM/day - KP^/day x 1 day/24 hrs. x 8 hr. (work day) x 1 x x 2.54 g/g - 0.85 x 10-3 g VCM/day (2) The total exposure to VCM from food contacting PVC packaging material may be estimated by solution of equation (3). (E) - [M]. x (G) x (B) (3) Where (E) is the effective total quantity of VCM in gested, [MJ, is the concentration of VCM in food, (G) is the total weight of food contacted (ingested) in g/ day, and (B) is the biological effectiveness of VCM in terms of its response at that dosage. If the following estimates for these factors are made, [M], - 1 x 10"8 g/g, (C) - 1.814 x 103 g/day (U5DA estimated daily food consumption, with the further assumption that 10% of all food consumed is packaged in PVC) and (B) - 1, then (E) is equal to 1.8 x 10~* g VCM/day. At this ingestion level, an inges tion dosage equivalent to the yearly inhalation dosage at 1 ppm for forty hours per week for forty-six weeks would require 300 years. If [MJ. -lx 10-* g/g (i.e. partition coefficient - 1000) an ingestion period of 3000 years would be required to equal the yearly inhalation dosage. While a number of assumptions have been made in these calculations, we feel that the estimate of (E) is very conservative and represents an order of cpagnitude approximation. The safety factors in this calculation are quite high: 1 The evidence for angiosarcoma in humans is for only a few individuals exposed (inhalation) to levels of 1000 ppm VCM for at least 10 years. 2 The biological effectiveness factor could easily be below one but is used at its maximum. 3 The partition coefficient (equationl) does not take into account the strong possibility that nonlinear de sorption at low VCM concentrations will greatly affect this factor, reducing it essentially to zero at some finite VCM level in the polymer. 4 10% of all food consumed is packaged in PVC. 5 No provision has been made for migration of VCM from the polymer into the atmosphere. Clearly this should be taken into consideration as losses of VCM by migration from the polymer to the atmosphere have been found in recent unpublished work. There appears, therefore, to be only a remote possibility of the demonstration of toxicity by inges tion of VCM migrating from properly controlled food grade PVC used in food packaging. Since in such a case we would be dealing with probabilities of risk to the general public rather than with certainties, there should be some assessment of the risks occurring from disruption of thoroughly de veloped procedures for protection of our food sup ply. For example, there is the clearly defined danger from highly toxic microbial toxins, including carcinogens, which could result from improperly protected foods due to a "Delaney" ban of PVC, A list of references follows. &43ZL-. Switch to side-loaded carton cuts 3-man line to one worker, doubles output capacity Fluidmaster Inc. is a leading producer of toilet waterlevei control valves sold to homeowners through home centers and hardware stores. The previous end-loaded Fluidmaster carton was high cost, both in material and in handling. Their new sideloaded carton costs substantially less... is much faster to form, load and close... and requires only ^ /3 the previous labor. Reference* 1. "Informal Fact Finding Hearing on Possible Hazard* ol Vinyl Chloride Manufacture and Use." U.S. Oepariment of Labor, Occupational Safely and Health Administration, February 15,1974. Data contained therein. 2. Manufacturing Chemists Association, Report ol April 16, 1974 u reported by Chem. Eng. News, p. 16, May 20,1974. I. Polyvinyl Chloride--H.A. Savretnicfc, pg. 1 (1969), Reinhold Book Corp. 4. Federal Register, Vol. 39, No. 101--Thursday, May 23,1974. Consumer Product Safety Commission (16C FR--Ran 1500). 5. Federal Register, Vol. 39, No. 92--Friday, May 10, 1974, Department of labor Occupational Safety and Health Administration (29C FR--Part 1910) (Docket OSH-36). i. Modern Packaging Encyclopedia, December 1973, pg. 02-66. McGrawHill Publishing Corp. 7. Federal Food, Drug and Cosmetic Aa, Subpart F of Seaton 121, as Amended in 1950. 0. Food and Drug Administration Guidelines (August, 1966) p. 0. 9. Code of Federal Regulations, Seaion 409C, 3A. 16. Wilks, R.A., and Gilbert, S.G. journal of Food Science, VoL 37,72 (1972). II. Varsano, J.L, Gilbert, S.G. Journal of Pharmaceutical Science, Vol. 62,07 (1973). 12. Varsano, |.L, Gilbert, S.G. Journal of Pharmaceutical Science, Vol. 62,92 (1973). 13. lieberman, E.R., Gilbert, S.G., and Shrinivasa, V., New York Academy of Sciences Transactions, Vol. 34, No. 0, December 1972. 14. Wilks, R.A. and Gilbert, S.G. Materials Research and Standards 0, 29 (I960). 15. ASTM Designation F151-72. Standard Method of Test for Residual Solvents in Flexible Barrier Materials. 16. Wilks, R.A. Ph.D. Thesis, Rutgers University (1971). 17. Rosen, ).D., Morano, J.R., Pareles. S.R., Glacln, J.R., and Gilbert, S.C. J. Assoc. Offic. Anal. Chem., July 197S (in press). 10. Pareles, S.R. and Rosen, |.D. Analytical Chemistry, Vol. 46,2056 (1974). 19, Kerens, A.R. Polymer Preprints, September 1974 (p. 197). _ URL 17423 devilment quiz Kay to Flutamastar's cost-cuthng packaging operation la thalr automatad 3macMna Una. Cartons ara tormag ana gtuad from btanka by Patan PG- V Format . . toadad by workar u wey paaa by on convayor... doaad and saalad by Patan CCY-0 Cloatr.. . and packad 5-wtda by 5-damp Into comtgatad cun by Bamay Packing & Cloaing Machine which also teals and ejecta toe caaaa to a holding convayor. Before: Three workers were required to insert the control valves into the 3" square end of 3 x 3 x 15" cartons... very much like stuffing items into close-fitting sleeves. Under pres sure to keep the line moving, workers tore many cartons which had to be scrapped. Now: With side-loaded cartons, a single worker literally drops the valve and fitting into the carton... filling as many cartons aa three workers filled before. / OTHER SAVINGS t Lower csrton costs: The new flit die-cut carton blanks cost $4.25 per M less than the pre-glyed folded blanks used pre viously. ' Less storage space: Delvered flak, 12,000 to a skid, the new blanks take up much less apace than the previous prs-glusd blanks which came pecked 200 to 4 corrugated case. Less handling times Peters PG-V holds 3000 die-cut blanks. The previous machine held only 100 pre-glued blanks, which kept a worker busy unloading cases and loading the machine every few minutes. ) Doubled output capacity: As Fluidmaster sales increase, it will be only e matter of machine adjustment to Increase packaging line speed. Peters machines are capable of forming cartons and closing & sealing cartons at speeds of more than 100 per minute... double toe present output. End-opening feature retained: Although side-loaded, the car tons are formed so they can be end-opened and reclosed in the store, permitting customers to examine toe contents before purchase. For more information on toe Peters machines used in the Fluid- master operation, write to Peters Machinery Company. 4700 N. Ravenswood Avenue, Chicago, Illinois 60640 or phone 312-561-9000. Readers are invited to contribute questions and their answers. The answers to these questions are on page 32. 1. What is the principal advantage of fourdrinier board over cylinder board when used in the manu facture of folding cartons? 2. In view of the interest in waste dis posal and recycling, what is the ad vantage of a cylinder board ma chine versus a fourdrinier board machine? 3. When manufacturing folding cartons, in which direction does the grain of the board normally run; vertically or horizontally around the carton? .4 What are the principal methods of forming rigid plastic containers? 5. What are the principal advantages claimed for ultra-violet drying inks used to print packaging materials? 6. Measurement of tinplate is by the base box. What is a base box equivalent to in terms of area? Credit: Submined by Dr. Harold |. Raphael, Director, Department of Packaging Science; Rochester Institute of Technology, Rochester, NY 14623 24 For more information on advertised products check Reader Service Card